Effect of Land Use Change on Organic Carbon Storage in Aggregates and Bulk Soil in Tootkabon Area, Guilan Province

Increasing anthropogenic disturbances, especially on land use change, is the major cause of soil quality deterioration in the world. Soil organic carbon has recently gained prominence in assessment of soil quality since it affects chemical, physical and biological aspects of the soil. This study was carried out to investigate the impact of land use change on some carbon fractions and carbon management index (CMI) in Tootkabon area, Guilan province. Three land uses (forest, dry farming, and rangeland) and three slope positions were selected. Soil sampling was done randomly from 0-15 cm depth of each land use and slope position. Particulate organic matter (POM) was measured in both bulk soil and aggregate particles and mineral associated organic matter (MOM) and extractable carbohydrate were measured in bulk soil. Carbon management index and carbon pool index were calculated using forest soil as a reference. Results showed that the highest and lowest amounts of particulate organic matter, mineral associated organic matter, and carbohydrate, and carbon pools were obtained in, respectively, forest and rangeland. Results also showed that the particulate organic matter in forest was increased by, respectively, 105% and 423% compared to dry farming and rangeland.[H1]  The highest percentage of particulate organic carbon was stored in macro aggregates, thus, the factors that control the stability and degradation of these aggregates can control soil organic carbon storage. Results showed that carbon pool index in dry farming and rangeland was decreased by, respectively, 45% and 82% compared to forest; and carbon management index in dry farming and rangelands was declined by 67% and 80.2%, respectively.